
#include<bits/stdc++.h>

#define int LL
using namespace std;
using LL = long long;
const LL LLINF = 1e18;
const int INF = 0x3f3f3f3f;
string s;

void solve()
{
    cin >> s;
    int ans = 0;
    for(int i = 0;i < s.size();i++)
    {
        for(int j = i;j < s.size();j++)
        {
            for(int k = j;k < s.size();k++)
            {
                if(s[i] == 'A' && s[j] == 'B' && s[k] == 'C')
                {
                    if(j - i == k - j)
                    {
                        ans++;
                    }
                }
            }
        }
    }
    cout << ans << endl;
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    //cin >> t;
    while(t--)
    {
        solve();
    }
    return 0;
}